1. Field of the Invention
The present invention relates to a flexible pipe connector, and more particularly to a pipe connector including a first cylindrical member and a second cylindrical member inserted into the first cylindrical member, the first cylindrical member defining, in an inner peripheral face thereof, an annular restricting groove, the second cylindrical member defining, in an outer peripheral face thereof, an annular attaching groove having a shorter axial length than the annular restricting groove of the first cylindrical member, the attaching groove being detachably attached with a radially deformable retaining member for coming into contact with an axial end face of the restricting groove for restricting range of relative axial movement between the two cylindrical members, the outer peripheral face of the second cylindrical member and the inner peripheral face of the first cylindrical member being provided with a radial opposing distance therebetween determined so as to allow insertion and withdrawal of the retaining member.
2. Description of the Related Art
In assembling an flexible pipe connector of the above-noted type, first, the second cylindrical member is inserted into the first cylindrical member, when a leading end of the second cylindrical member is placed at an axially intermediate portion of the restricting groove defined in the inner peripheral face of the first cylindrical member. Then, through the annular gap formed between the outer peripheral face of the second cylindrical member and the inner peripheral face of the first cylindrical member, the retaining member which is being radially expanded is inserted from the leading end of the second cylindrical member to the attaching groove of the same. In this condition, the radially expanded condition of the retaining member is released to allow this retaining member to be reduced radially to elastically fit the attaching groove.
As described above, with this type of flexible pipe connector, the annular gap for insertion/withdrawal of the retaining member is formed between the outer peripheral face of the second cylindrical member and the inner peripheral face of the first cylindrical member. Therefore, an external force in the withdrawing direction generated in association with an earthquake or differential settlement affects both of the two cylindrical members which are un-withdrawably and expandably connected to each other within the movable range determined by the length of the restricting groove. In this, the retaining member fitted to the attaching groove of the second cylindrical member is strongly pressed in the axial direction against one end face of the restricting groove located on the side of the entrance opening of the first cylindrical member, when the retaining member is urged to elastically deform or expand radially, so that this retaining member may be inadvertently detached or withdrawn from the attaching groove of the second cylindrical member.
For this reason, a conventional flexible pipe connector has a construction shown in FIG. 12. In this construction, a contact face 50a of the restricting groove 50 and a contact face 51a of the retaining member 51 are formed respectively as a tapered face having a decreasing diameter toward the entrance opening (a) of the first cylindrical member A, so that these tapered contact faces 50a, 51a come into contact against each other in the axial direction when such withdrawing-direction external force is applied to the two cylindrical members A, B. And, the tapered contact face 50a of the restricting groove 50 has a minimum diameter which is same as or smaller than a minimum outside diameter of the tapered contact face 51a of the retaining member 51 (see Japanese un-examined utility model gazette No. 4-136392 for example).
In the case of the conventional flexible pipe connector having the above-described construction, when the withdrawing-direction external force is applied to the two cylindrical members A, B to cause the tapered face 51a of the retaining member 51 fitted to the attaching groove 52 of the second cylindrical member B and the tapered face 50a of the first cylindrical member A to come into contact against each other, the retaining member 51 is strongly pressed against the inner peripheral face of the attaching groove 52 of the second cylindrical member B. Thus, there occurs mutual sliding movement between the tapered face 51a of the retaining member 51 and the tapered face 50a of the first cylindrical member A. In association with this mutual sliding movement, the portion of the first cylindrical member A on the side of the entrance opening (a) thereof elastically deforms in the radially outward direction and the portion of the second cylindrical member B on the side of its inserted end side elastically deforms in the radially inward direction. And, if the sum of the amounts of these elastic radial deformations of the two cylindrical members exceeds a radial engagement width L between the tapered face 51a of the retaining member 51 and the tapered face 50a of the first cylindrical member A, the retained condition between the two cylindrical members A, B is forcibly released.
Therefore, in order to improve the retention condition between the cylindrical members A, B, it is necessary to increase the radial engagement width L between the tapered face 51a of the retaining member 51 and the tapered face 50a of the first cylindrical member A. But, such enlargement of this width tends to result in radial enlargement of the entire pipe connector.
The present invention attends to the above-described state of the art, and its primary object is to provide a flexible pipe connector which may be formed compact in the radial direction and which yet is capable of preventing inadvertent withdrawal of the two cylindrical members more effectively.